Induction coil



Apri 14, 1925. 1,533,797

v. GRI-:IFF ET AL INDUCTION COIL Filed June 4, 1921 -INVENTOR 92 LES/.lf CURT/S &

VCTOR GRf/FF MQ: t QAMBQ, @wm

ATTORNEY Patente-d Apr. 14, 1925i.v I

UNITED STATES.

1,533,797 PATENT .-oFyFicE.

'VICTOR GREIFF, OF NEW YORK,N. Y.,`N1) LESLIE FORREST CURTIS, 0F SPRING- FIELD, MASSACHUSETTS, ASSIGNORS TO AMERICAN BOSCH IVIAGNETO CORPORAF TION, vOli' SPRINGFIELD, MASSACHUSETTS, A CORPORATION 0F NEW YORK.

INDUCTION COIL.

Application filed :unel 4,

and 'we do hereby declare the following to bei a full, clear, and exact description of the invention, such as will enable others skilled in the art to vwhich it'appertains to make and use the same'- i Thevpresent invention relates to induction coils having primary and secondary windings mounted lon a core.

In some cases, such coils had a closed mag` netic circuit made up of the core and continuous extensions embracing the windings at the ends and outside thereof, or else an incomplete magnetic circuit with one or both of the end portions omitted. Incoils 'with the closed magnetic circuits, the primary current does not rise sufficiently rapidly to produce a satisfactory sparking voltage in the secondary winding at some necessaryhigh speeds of interruption, and where one or both of the end plates is omitted, the core is not suiiciently magnetized to. produce a satisfactory sparking voltage with the desired primary Winding. In accordance with thisv part ofl ourinvention, amore suite able magnetic circuit is obtained for pro-' ducing ignition sparks at the spark plugs of an internal combustion engine into -var1` ous numbers of cylinders. and operating at various speeds, by providing a peripherally discontinuous i magnetic shell around. the

windings'in combination witlr a magnetic plate at-either or both endsysaidend plate or plates being s aced from said shell, and preferably also roml theA core, to form a plurality vof airgaps in'the Ina,f. eI 1eticy circuit, and also bemg,l preferably, angularly discontinuous to form air gaps vwhereby using the shell as a contact member whichl eddy currents in the end plates will be avoided.

Whether or not the shelll is of magnetic material, and whether or notthe end plates are used, the invention also comprehends may be electricallyconnected to the terminal 1921. Serial No. 474,995.

of the secondary winding so as to.y form a connecting element between the secondary winding and the high tension binding post of the coil. For the purpose of conveniently attaching theignitiondead to the high tension binding post, the latter may be adjusted in position by adjustably mounting the tube to which the post is connected. To obtain a simple and eiiicient electrical connection, a Contact spring, preferably in the form of a bow-spring, presses against the shelll which in turn is pressed against vthe terminal o the secondary winding.

, In the accompanying ing our invention in application, as an example to an induction coil for ignition systems for internal combustion enginesz" Fig. 1 is a longitudinal sectional'view of the coil; Fig. 2 is a transverse sectional view drawings illustratf taken on line 2 2 of Fig. l; Fig. 3 is anv end View ofthe coil showing vthe mode of connecting the terminals; Fig. 4 is a fragmentary sectional view showing the mode of making electrical connection with the terminal of the secondary winding, and Fig. 5 is a diagrammatic-view showing the wiring diagram of the circuits connected tothe coil and parts of an ignition system.

Referring more particularly to the drawing, the coil comprises an encasingstructure having end capsl and 2 and an interposed tube 3 adapted to surround the coil proper. The latter'comprises a tube 4 of insulating material uponwhich is wound the primary winding v5. Upon the latter is wound lthe secondary winding 6 which. as is clearly shown in Fig.4 1, is-of shorter 'length than' .with insulating vmaterial '1n any suitable mannen if: desired.V Abutting the ends of the primary' windin and the paper portions and upon the tube 4 are located insulating washers or discs 8 and 9, and adi jacent these washers` are located lend plates 10 and 11 each composed of a pair of discs of magnetic material, and also being preferablyv cut radially to -provide a radial-slot or air gap whereby eddy currents in these discs fwill'be avoided. Adjacent these venol plates 4inwardly ytoward each other for a short distance to cover the ends of the paper portions 7. These members 12 and13 also have adjacent thereof, metal clip plates -14 and 15 eachprovided with clip portions 16, 17 and 18 for connection with the terminals of the windings, as will more fully hereinafter ap` pear. Each of the end plates 10 and 11, the members 12 and 13 and the plates 14 and 15 are connected together by rivets 19 and 20, whereby the connected members form unitary members located at the endsof the windings. A

@n the outside of the secondary winding so as to almost completely surround it, is located a shell 21 of magnetic material, the opposed edges'22 and 23 of which, however, are spaced from each other, as is clearly shown in theY lower portion of Fig. 2 of the drawing, the shell being in the form of an open cylinder split along one side thereof.

, This shell s thus made peripherally discon tinuous in vorder to prevent eddyA currents.

It will also be observed that this shell is preferably of the same length as the secondary winding, whereby spaces are pro- -vided between the ends of the shell 21 and' the marginsof the end plates 10 and 11, to' form air. or reluctance gaps and electricalK clearances therebetween. Strips of tape 24 and 25 may thenbe woundabout the coil assembly over the ends of the shell 21 and the flanges of the members 12 and 13, so as to maintain the end caps and connected parts in lixed spaced relation with respect to the ends of the shell 21. Strips of tape 26 may also be laid over the opposed edges22 and 23 and with the ends thereof included beneath the wound strips 24 and 25. p

Within the tube 4 are located two `groups of magneticI laminations 27 of angle form in cross-section so arranged so as to provide between said groups .a fixed passage 28 through which extends a tie boltA 29, the

latter being thus centrally located. It will thusbe observed that the end plates 10 and 11 being located upon the tube y4 will also bespaced from the core 27 by at leastthe thickness of the tube 4 so as .to form therebetween reluctance gaps. The end caps 1 and 2 are ofidentical structure and are'pro-l vided with annular grooves -30 and' 31 inv which extended the ends of the tubular member 3, suitable asking 32 and 33, such as felt, bein provided in saidgrooves at the ends of t ie tube 3. The caps 1 and 2- are also centrally recessed to receive the ends of the tube 4 and are provided with projections 34 and 35 extending :radially inwardly in said recess and into end slots formed in thev ends ofthe' tube 4 whereby rotation of the latter with respect tothe caps 1 and 2 is prevented. Within the open ends of the tube 4 and in abutting relation to the ends of the corel laminations 27 are located felt washers 36 and 37 adapted to maintain said :laminations from longitudinal movement in said tube.

The caps l and 2 are centrally apertured to receive the bolt 29 which 'is provided at one end ,with a screw head 38 reposing in a suitable recess formed therefor in the cap 1, and threaded at the other end to receive a nut 39 located in a similar recess in the head r3. rlhecaps 1 and are also eccentrically apertured to receive binding posts bolts 4) and 41 having heads 42 and 43 located in suitable recesses formed on the inner side of the caps, and threaded at the outer ends to receive nuts 44 and 45 also located within suitable-recesses formed in the -outer portion of the caps 1 and 2. The

threaded ends of the bolts 29 and 41 are of sufficient length to receive thereonv a pair of grooved porcelain pieces 46 and 47, which when located adjacent each other with the grooves in `juxtaposed relation, for@ a recess for a ballast coil 48. TWithin apertures, formed in the porcelain members 4 6 and 47, for receiving the bolts' and 41, are contained sleeve members 49 and 50 which are in metallic Contact with the threaded portion of said bolts. The ballast coil is connected at its ends to these sleeves whereby current passing therethrough may pass from one bolt to the other. Upon the outer ends of the bolts 29 and 41 are provided nuts 51 and 52 for binding the porcelain pieces 46 and 47 with the cap 2, while the nut 39, and the head 38 of the bolt 29 serve the purpose .of binding the caps 1 and 2 against the ends of the tubes 3 and 4, as is readily apparent :trom the illustration made in F ig. 1 of the drawing. The outer end of the bolt 29 also has a binding nut 53 for the connection of a lead 54 running to the batte 55. The terminals of the primary winding extend through slots 56 formed in the washers 8 and 9, end plates 10 and 11 and members 12 and 13 withthe bared portion 57 .bf such terminals extending into .the clip' 16 which is compressed about the end of such terminal to permanently hold the same 'fixed theretoi Short cable pieces 58 and 59 are clamped on the respective plates 14 and 15 by means of .clips 18 and have a bared end 60 clamped in clip 17 and theother bared end 61 located in slots suitably provided in thevhca'dsl 42 and 43 and soldered or otherwise-suitably fastened thereto, as is clearly shown 'in F ig. 3. On the threaded end of .the bolt '40 is also provided a binding nut 62 between which and the nut 44 may be secured, the terminal for a lead 63 running to an interrupter 64.

Thetube 3 carries a binding post construction 65 comprising a bolt 66, a thumb nut 67, threaded thereon at its'vouter end.

insulating members 68 and 69, and ahead 70 formed 4upon the inner end of the bolt 66. The head 70 extends within vthe interior of the tube 3 and has clamped between it and the inner surface of the tube 3 a bowspring 71 which constantly bears or presses .against the outer surface of the magnetic contact between the strip 73 and the shell 21, as well as between theshell 21 and the springv 71,;irrespective of the position to which the tube 3 is adjusted by turning it in the grooves 30 and 31 about the axis of the bolt 29 and the caps 1 and 2. The other end ,ofthe secondary circuit has its lead connected to theterminal 5,7 ot the'primary winding, as is clearly shown in Fig. 5.

When installing the induction coil in an ignitionv system, it is often required to locate it in different positions and in di'erent relations to the parts of the system, and it has been found that when the high tension binding post 65 is connectedl in ixed rela-v tion to the coil structure, that it'is often very inconvenient to connect the high tension lead 74'running from the coil to the distributor. For the purpose of convenience, the tube 3 has been made angularly adjustable so that it may be located in the position shown in full lines in Fig. 2 ot the drawing or in any other position, such as is shown in dotted lines of said figure. During such adjustment, however, the bowspring 71 will always maintain contact with the magnetic shell 21 so that thei'electrical connection between the secondary winding and thehigh tension binding post will not be changed..

By making the core of laminated sheetsv or strips of angle form, it, isfpossible to so arrange and locate the same within the tube 4, so as to provide a permanently shaped passage between the groups thereof. so that the bolt 29 may be easily introduced lengthwise through the core without in any way disturbing the elements of the core. ln

order to obtain the proper reluctance in the magnetic circuit of the core, the end plates andthe magnetic shell, the end plates are spaced from the core and the shell to provide air gaps of suitable size, so that when theprimary circuit 1s .interrupted and the cuent dropstherein, the induction of potential in the secondary circuitwill be more 'i edective. This greater -edectiveness is ob tained by reason of the fact that the reduction of the flux, from a maximum to a value when no current is flowing in the primary circuit, will be greater and more rapid. By use of the air gaps, poles are created on portions o the magnetic material, thus exerting a more rapid demagneti'zing effect.

Referring to the diagram shown in Fig. 5, the' primary circuitv includes the battery 55 lead 54, bolt 29, ballast coil 48, bolt 41, primary winding 5, bolt 40, lead 63, interrupter mechanism 64, grounds 76 and 77, and lead 78 connected to the battery. A

ycondenser 7 9 is connected across the contacts spark: plugs 81 and ground 82. rll`he operation of the device is believed to be otherwise clear.

i Having thus described our invention what we claim is:

1. An induction coil having a core with primary and secondary windings mounted thereon, an encasin structure including a tube and a high tension binding post, a magnetic shell around said windings and electrically connected to the terminal of said secondary winding and said .binding post. 2. An induction coil having a core with primaryv and secondary windings mounted thereon, an encasing structure including a tube and a high tension binding post, a peripherally discontinuous magnetic shell around said windings and electrically connected to the terminal of said secondary winding and said binding post.

3. An induction coil having a. corewith primary and secondary windings mounted thereon, an encasing structure including an adjustable tube carrying a high tension binding post, a contact member around said windings and electrically connected to the terminal of said secondary winding and said 4binding post in any adjusted position of said .tube and post.

4. An kinduction coil having a core with for maintaining the same in intimate `contact with the terminal of said secondary winding in an adjusted position of said tube and post. l

ln testimony whereof we aiiix our signatures.

4vieron Guaira.

Lnsmn nonna-sr onnris. 

